Oxidation Of Residues Research Articles

Elucidating the relation between residual oxidants formation behavior and quinolone antibiotic removal efficiency on catalytic ozonation in seawater-based aquaculture wastewater

Owing to the recent developments in aquaculture, the discharge of antibiotic-laden wastewater has become a growing concern. Quinolone antibiotics, which cause central nervous system and cardiac conduction disorders, are commonly detected in aquaculture wastewater. To remove antibiotics in wastewater, the ozone process is a commonly utilized method. In the process of seawater ozone treatment, bromide ions (Br−) produce total residual oxidant, such as hypobromous acid (HOBr). However, the oxidation potential of the total residual oxidant (TRO) is lower than that of ozone, and the presence of inhibitors, such as ammonium, and dimethyl sulfide can reduce the residual oxidant concentration. Therefore, the seawater ozone process requires a higher ozone injection than freshwater. In this study, various factors affecting TRO production were evaluated to determine the optimal ozone-catalytic process using gamma-alumina and elucidate the relationship between TRO production and antibiotic removal efficiency for efficient seawater-based wastewater treatment. The removal rates of representative quinolone antibiotics, such as enrofloxacin, ciprofloxacin, and oxolinic acid, were evaluated using liquid chromatography-fluorescence detection. The addition of a catalyst enabled the reaction to maintain a higher TRO concentration and improves antibiotic removal efficiency, even in the presence of ammonium in the aquaculture wastewater with the same ozone dosage applied. The results reveal that the ozone-catalyst process contributes to increased TRO production to suppress bacterial growth and effectively remove non-degradable organic matter, such as antibiotics, in seawater-based wastewater treatment.

Copper catalyzed Shono-type oxidation of proline residues in peptide.

Since the initial report in 1975, the Shono oxidation has become a powerful tool to functionalize the α position of amines, including proline derivatives, by electrochemical oxidation. However, the application of electrochemical Shono oxidations is restricted to the preparation of simple building blocks and homogeneous Shono-type oxidation of proline derivatives remains challenging. The late-stage functionalization at proline residues embedded within peptides is highly important as substitutions about the proline ring are known to affect biological and pharmacological activities. Here, we show that homogenous copper-catalyzed oxidation conditions complement the Shono oxidation and this general protocol can be applied to a series of formal C-C coupling reactions with a variety of nucleophiles using a one-pot procedure. This protocol shows good tolerance toward 19 proteinogenic amino acids and was used to functionalize several representative bioactive peptides, including captopril, enalapril, Smac, and endomorphin-2. Last, peptide cyclization can also be achieved by using an appropriately positioned side-chain hydroxyl moiety.

Behavior of residual Zn oxides in metallized pellets applied in the converter steelmaking process

Metallized pellets serve as a significant recycling product derived from the iron and steel production, comprising dust and sludge. However, the substantial presence of residual zinc within these pellets poses challenges such as vaporization, condensation, and accumulation, ultimately leading to severe clogging in off-gas pipes and potential erosion of refractory materials. To address this, a novel approach is proposed to efficiently harness the potential of metallized pellets within the converter process, focusing on investigating the behavior and mechanism of zinc oxides. Results reveal that metallized pellets introduce Zn elements with a distribution ratio of approximately 1:1 in the steel-gas phase and only around 3% in the slag. The Zn element can remain stable in the over-oxidized molten steel, and an inverse proportional relationship between [C] and [Zn] contents in the molten steel has been derived from industrial and laboratory experiments as follows.[%C]0.84·[%Zn]=0.0055Furthermore, the end-point Zn content in the molten steel is closely related to the C content in the molten steel before the addition of the metallized pellets. The ZnO contained within the metallized pellets must undergo reduction by the [C] present in the molten steel, as well as by the [C] to facilitate vaporization and escape. Consequently, a critical carbon content (approximately 0.3%) emerges, wherein the addition of metallized pellets enables the maximum and enduring presence of Zn elements within the molten steel while minimizing vaporization and escape of Zn into the off-gas pipeline.

The role of sperm-specific glyceraldehyde-3-phosphate dehydrogenase in the development of pathologies-from asthenozoospermia to carcinogenesis.

The review considers various aspects of the influence of the glycolytic enzyme, sperm-specific glyceraldehyde-3-phosphate dehydrogenase (GAPDS) on the energy metabolism of spermatozoa and on the occurrence of several pathologies both in spermatozoa and in other cells. GAPDS is a unique enzyme normally found only in mammalian spermatozoa. GAPDS provides movement of the sperm flagellum through the ATP formation in glycolytic reactions. Oxidation of cysteine residues in GAPDS results in inactivation of the enzyme and decreases sperm motility. In particular, reduced sperm motility in diabetes can be associated with GAPDS oxidation by superoxide anion produced during glycation reactions. Mutations in GAPDS gene lead in the loss of motility, and in some cases, disrupts the formation of the structural elements of the sperm flagellum, in which the enzyme incorporates during spermiogenesis. GAPDS activation can be used to increase the spermatozoa fertility, and inhibitors of this enzyme are being tried as contraceptives. A truncated GAPDS lacking the N-terminal fragment of 72 amino acids that attaches the enzyme to the sperm flagellum was found in melanoma cell lines and then in specimens of melanoma and other tumors. Simultaneous production of the somatic form of GAPDH and sperm-specific GAPDS in cancer cells leads to a reorganization of their energy metabolism, which is accompanied by a change in the efficiency of metastasis of certain forms of cancer. Issues related to the use of GAPDS for the diagnosis of cancer, as well as the possibility of regulating the activity of this enzyme to prevent metastasis, are discussed.

Morphology and Size Distribution of Condensed Combustion Products of Aluminum-Based Propellants

ABSTRACT Both glycidyl azide polymer (GAP) and hexanitrohexaazaisowurtzitane (CL-20) are high-energy compounds with very promising applications. However, there are relatively few relevant studies for GAP/CL-20 aluminum-based propellants. In this paper, the CCPs of aluminum-based GAP/CL-20 propellant under different operating conditions were collected by a gas collecting device, and the physicochemical properties of CCPs were carefully studied by various modern analytical and testing instruments. The results show that the CCPs consist mainly of smoke oxide particles (~1 μm), residual oxide particles (~20 μm) and agglomerates. Residual oxide particles are widely available, but have received less attention from researchers. The agglomerates can be divided into two categories: sphere-like agglomerates and non-spherical agglomerates. Sphere-like agglomerates include cracked spheres, solid spheres, hollow spheres, and spheres with oxide caps. Surprisingly, we found an agglomerate with two caps. Non-spherical agglomerates are larger in size than sphere-like agglomerates, and the non-spherical agglomerates include irregular agglomerates, coral-like aggregates, and filamentous agglomerates. As far as we know, coral-like aggregates and filamentous agglomerates in CCPs have not been reported in the literature. Pocket theory and inter-pocket bridge theory were used to explain the formation mechanism of fine filament agglomerates. In addition, the formation mechanisms of different types of agglomerates were analyzed and sorted out. The particle size distribution of CCPs at different pressures shows that the average particle size of CCPs decreases with increasing pressure. It is hoped that this paper can provide a reference for the design of high-energy propellant formulations.

The evolution of selective autophagy as a mechanism of oxidative stress response: The evolutionarily acquired ability of selective autophagy receptors to respond to oxidative stress is beneficial for human longevity.

Ageing is associated with a decline in autophagy and elevated reactive oxygen species (ROS), which can breach the capacity of antioxidant systems. Resulting oxidative stress can cause further cellular damage, including DNA breaks and protein misfolding. This poses a challenge for longevous organisms, including humans. In this review, we hypothesise that in the course of human evolution selective autophagy receptors (SARs) acquired the ability to sense and respond to localised oxidative stress. We posit that in the vicinity of protein aggregates and dysfunctional mitochondria oxidation of key cysteine residues in SARs induces their oligomerisation which initiates autophagy. The degradation of damaged cellular components thus could reduce ROS production and restore redox homeostasis. This evolutionarily acquired function of SARs may represent one of the biological adaptations that contributed to longer lifespan. Inversely, loss of this mechanism can lead to age-related diseases associated with impaired autophagy and oxidative stress.

Direct diffusion bonding of 1060Al processed by surface activation with various doses of Ar ion bombardment

In this work, the microstructure and properties of the 1060Al surface after bombardment with different doses of Ar ion and the evolution rule of the quality of the subsequent solid-state diffusion bonded joints have been investigated in detail. The results showed that the oxide layer could be removed completely at an appropriate ion bombardment dose (2 × 1018ion/cm, while kept the same energy of 1 keV), the roughness of the surface was also reduced, crystal defects such as dislocation loops formed near the surface, all of the above factors were beneficial for diffusion bonding. Well-bonded joints with a bonding ratio of ∼97.7% and a shear strength of ∼45.9 MPa could be obtained even at lower process parameters (450 °C/90 min, 5 MPa). When the bombardment dose was too low, the residual oxide film and the rough surface were not conducive to atomic diffusion at the interface, resulting in the unbonded defects in the joint. While the irradiated expansion of the 1060Al surface occurred when the bombardment dose was too high, and the bulges would crack under pressure. In both cases, it could not obtain a well-bonded interface, the joints showed a lower shear strength.

Superacid Resin-Based Heterogenous Catalysts for the Selective Acylation of 1,2-Methylenedioxybenzene.

In this work, we firstly report on the use of highly active and selective Aquivion superacid resins as heterogeneous catalysts for the acylation of 1,2-methylenedioxybenzene (MDB) with propionic anhydride (AP). The reaction was investigated and optimized using solvent-free conditions to selectively produce 3,4-methylenedioxypropiophenone (MDP1P), a key intermediate for the manufacture of active ingredients used in insecticide formulations with a volume of production of roughly 3000 t/y. Interestingly, Aquivion-based catalysts allows to work in mild reaction conditions (i.e. 80 °C), obtaining MDP1P yields as high as 44 % after only 1 h of reaction (selectivity 83 %). A detailed study of the AP reactivity demonstrated its tendency to promote oligomerization reactions that, as confirmed by ex-situ and in-situ FT-ATR analyses, caused the deactivation of the catalyst forming surficial carbonaceous residues. In this context, a fast oxidation of the resin surface organic residues using a diluted HNO3 (or H2O2) solution was proven to be an efficient method to regenerate the catalyst, which can be reused for several reaction cycles. The results obtained in preliminary scale-up tests were basically unaffected by the reaction volume (up to 800 mL), paving the way for possible future applications of the process.

Tailored Chemical Reactivity Probes for Systemic Imaging of Aldehydes in Fibroproliferative Diseases.

During fibroproliferation, protein-associated extracellular aldehydes are formed by the oxidation of lysine residues on extracellular matrix proteins to form the aldehyde allysine. Here we report three Mn(II)-based, small-molecule magnetic resonance probes that contain α-effect nucleophiles to target allysine in vivo and report on tissue fibrogenesis. We used a rational design approach to develop turn-on probes with a 4-fold increase in relaxivity upon targeting. The effects of aldehyde condensation rate and hydrolysis kinetics on the performance of the probes to detect tissue fibrogenesis non-invasively in mouse models were evaluated by a systemic aldehyde tracking approach. We showed that, for highly reversible ligations, off-rate was a stronger predictor of in vivo efficiency, enabling histologically validated, three-dimensional characterization of pulmonary fibrogenesis throughout the entire lung. The exclusive renal elimination of these probes allowed for rapid imaging of liver fibrosis. Reducing the hydrolysis rate by forming an oxime bond with allysine enabled delayed phase imaging of kidney fibrogenesis. The imaging efficacy of these probes, coupled with their rapid and complete elimination from the body, makes them strong candidates for clinical translation.

Study on total residual oxidant decay in long-distance seawater intake pipeline of cooling system

Electrochlorination is often used for biofouling control along the water intake pipeline of seawater cooling system, but with the increasing of pipeline length, this process needs to be further improved. In this study, the dynamic circulation and field pilot test were used to simulate the long-distance seawater intake pipeline, investigating total residual oxidant (TRO) decay and its influencing factors by comparing the bench test. The results showed that intermediate dosing could increase terminal TRO, but also reduce the CT value, resulting in decline of local inactivation effect. The initial concentration of dynamic cycle test was higher than that of bench test under the same terminal TRO, and the difference value between the two was affected by holding time. When the initial concentration was greater than 8.5 mg L−1, TRO decay rate was proportional to the seawater flow rate and inversely proportional to the initial concentration. The initial concentration of 8.5–10 mg L−1 could meet TRO decay requirement under 3 h holding time, and the dosing concentration could be reduced to 6 mg L−1 when the temperature was low. The results provided important guidance for the actual operation of biofouling control in long-distance water intake pipelines of cooling system.

Analytical method development, validation, and out-of-specification investigations for polyethylene glycol

This work was motivated by the United States Pharmacopeia monograph modernization initiative and European directorate for the quality of medicines and healthcare. An out-of-specification (OOS) occurrence prompted OOS investigations for the cGMP (cGMP refers to the Current Good Manufacturing Practice regulations enforced by the FDA) release testing of residual ethylene oxide in polyethylene glycol (PEG) according to the standards detailed within the United States Pharmacopeia/National Formulary (USP-NF) for polyethylene glycol, and the European Pharmacopoeia (Ph. Eur.) for macrogols. During the OOS root cause investigations, we observed a PEG degradant and identified it as methyl formate, which co-elutes with ethylene oxide using the GC (gas chromatography) methods published in current USP-NF and Ph. Eur. for PEGs. To address this, a novel method utilizing static headspace gas chromatography with flame ionization detection (HS-GC-FID) was developed to test various grades of PEGs for the presence of residual ethylene oxide, along with other process related impurities and degradation products. With this new method, ethylene oxide, a known genotoxic impurity and IARC (International Agency for Research on Cancer) Class 1 human carcinogen, can be well resolved from methyl formate, a newly identified and comparatively innocuous degradant derived from PEG. The currently available official compendial methods are unable to separate the specific impurities in PEGs. However, the new GC method presented in this paper has been shown to have a high and unique selectivity, allowing for baseline separations (chromatographic resolutions greater than 1.5) of all related impurities in PEGs, which is a challenging task. Additionally, this method has been found to be stability-indicating based on a forced degradation study. During stress stability study of PEGs involving acid, alkali, heat, light, and oxidation, some other PEG degradants, including formaldehyde, were identified. It is possible that formaldehyde undergoes a disproportionation reaction known as the Cannizzaro reaction, leading to the formation of formic acid and methanol. The formic acid then undergoes an esterification reaction with methanol to produce methyl formate. To the best of our knowledge, this is the first stability-indicating HS-GC-FID method that accomplishes this separation in a single run, and it was successfully validated as per ICH (the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use) guidelines. Therefore, this method is suitable for the conduct of cGMP batch release and stability testing of PEGs in regulated quality control (QC) laboratories.

Methionine sulfoxide reductases and cholesterol transporter STARD3 constitute an efficient system for detoxification of cholesterol hydroperoxides

Methionine sulfoxide reductases (MSRs) are key enzymes in the cellular oxidative defense system. Reactive oxygen species oxidize methionine residues to methionine sulfoxide, and the methionine sulfoxide reductases catalyze their reduction back to methionine. We previously identified the cholesterol transport protein STARD3 as an invivo binding partner of MSRA (methionine sulfoxide reductase A), an enzyme that reduces methionine-S-sulfoxide back to methionine. We hypothesized that STARD3 would also bind the cytotoxic cholesterol hydroperoxides and that its two methionine residues, Met307 and Met427, could be oxidized, thus detoxifying cholesterol hydroperoxide. We now show that in addition to binding MSRA, STARD3 binds all three MSRB (methionine sulfoxide reductase B), enzymes that reduce methionine-R-sulfoxide back to methionine. Using pure 5, 6, and 7 positional isomers of cholesterol hydroperoxide, we found that both Met307 and Met427 on STARD3 are oxidized by 6α-hydroperoxy-3β-hydroxycholest-4-ene (cholesterol-6α-hydroperoxide) and 7α-hydroperoxy-3β-hydroxycholest-5-ene (cholesterol-7α-hydroperoxide). MSRs reduce the methionine sulfoxide back to methionine, restoring the ability of STARD3 to bind cholesterol. Thus, the cyclic oxidation and reduction of methionine residues in STARD3 provides a catalytically efficient mechanism to detoxify cholesterol hydroperoxide during cholesterol transport, protecting membrane contact sites and the entire cell against the toxicity of cholesterol hydroperoxide.

Combustion synthesis of Eu2O3 nanomaterials with tunable phase composition and morphology

Combustion reactions in europium nitrate – acetylacetone – 2-methoxyethanol solutions and gels were investigated to produce europium (III) oxide (Eu2O3) nanocrystalline materials and thin films. Thermal analyses of solutions indicated that the 2-methoxyethanol solvent also acts as a fuel in the absence of acetylacetone. Adding acetylacetone increases the overall heat of the reaction. Thermal analysis results revealed that the slow oxidation of unburned hydrocarbon residues follows the primary combustion reaction. Time-temperature profile measurements of the bulk combustion synthesis process in air and nitrogen atmospheres enabled the extraction of the maximum reaction temperature and the heating and cooling rates in the combustion zone. Several direct correlations exist between measured combustion parameters and the phase composition of the products. Combustion in air results in mixed-phase cubic and monoclinic nanocrystalline Eu2O3. Increasing the acetylacetone concentration in solutions increases the synthesis temperature and decreases the quantity of cubic Eu2O3. The reaction of solutions in a nitrogen atmosphere or diluted with Eu2O3 provides control of the product phase composition and reduces the quantity of the monoclinic phase. Transmission electron microscopy imaging shows that the Eu2O3 end products are highly porous aggregates of nanocrystalline particles. Electrospraying of reactive solutions onto different substrates followed by short annealing makes the preparation of Eu2O3 materials with diverse morphologies possible.

Expanded bioinformatic analysis of Oximouse dataset reveals key putative processes involved in brain aging and cognitive decline

The theory that aging is driven by the damage produced by reactive oxygen species (ROS) derived from oxidative metabolism dominated geroscience studies during the second half of the 20th century. However, increasing evidence that ROS also plays a key role in the physiological regulation of numerous processes through the reversible oxidation of cysteine residues in proteins, has challenged this notion. Currently, the scope of redox signaling has reached proteomic dimensions through mass spectrometry techniques. Here, we perform a comprehensive bioinformatics analysis of cysteine oxidation changes during mouse brain aging, using the quantitative data provided in the Oximouse dataset. Interestingly, our unbiased analysis identified hundreds of putative cysteine redox switches covering several pathways previously associated with aging. These include the ubiquitin-proteasome pathway and one-carbon metabolism (folate cycle, methionine cycle, transsulfuration and polyamine pathways). Surprisingly, cysteine oxidation changes are enriched in synaptic proteins in a highly asymmetric distribution: while postsynaptic proteins tend to increase cysteine oxidation with age, the opposite occurs for presynaptic proteins. Additionally, cysteine oxidation changes during aging are associated with proteins involved in the regulation of the mitochondrial transition pore opening and synaptic calcium homeostasis. Our analysis reinforces the concept that brain aging is associated with selective changes in the oxidation state of key proteins, rather than an overall trend toward increased oxidation. Also, we provide a prioritized list of specific cysteine residues with putative impact in aging processes for future experimental validation.

Improving hydrogen peroxide stability of a dye-decolorising peroxidase from Irpex lacteus F17 by site-directed mutagenesis

Il-DyP4, a dye-decolorizing peroxidase (DyP) from Irpex lacteus F17, has a strong ability to oxidise harmful aromatic compounds, implying application potential in the field of environmental protection. However, the low H2O2 stability of Il-DyP4 hinders its practical application. To improve the H2O2 stability of Il-DyP4, oxidation-sensitive amino acids including three Met, one Cys and ten Tyr residues were mutated to less easily oxidizable residues such as Leu, Val and Phe by site-specific mutagenesis. Mutation of the M207 site, located on the surface of the enzyme and far away from the haem group, improved H2O2 stability by 5.3-fold or more. In addition, Y234, also on the enzyme surface, was replaced with Phe and the Y234F mutant displayed 7.3-fold increased H2O2 stability. Furthermore, mutants M207V and Y234F were selected for the decolorization of various types of synthetic dyes, revealing high decolorization activities, especially for M207V with enhanced catalytic activity. The stable DyP mutant M207V has the potential for decolorization of industrial dye wastewater.

Microstructural and micro-mechanical behaviours of friction stir processed magnesium alloy

This investigation deals with the microstructural and mechanical behaviours of friction stir processed (FSPed) commercially available pure magnesium with different tool profile geometry. The micro-level properties were assessed through in-situ micro-pillar compression which showed that FSPed material experienced significant plastic deformation and even re-distribution of residual oxide particles which was present in the cast magnesium together with grain refinement (from 3.4 μm to 2.6–2.7 μm). These changes in microstructure contributed to raise the compressive and yield strengths of the FSPed magnesium, up to 99 MPa and 94 MPa respectively, compared to 33 MPa of cast magnesium, when triangular tool profile was employed. Furthermore, the deformed material acquires ductile breakage with improved plasticity (micro-necking) irrespective of processing conditions, that is, either cast or friction stir processed.

Using KNbO3 catalyst produced from a simple solid-state synthesis method in a new piezophotocatalytic ozonation hybrid process

The present work reports the development and application of potassium niobate (KNbO3) as a catalyst in a novel hybrid piezophotocatalytic ozonation process aimed at wastewater remediation. Pure KNbO3 samples were produced through a simple solid-state synthesis using water-soluble ammonium niobate (V) oxalate hydrate (C4H4NNbO9·xH2O) as niobium source, employing different potassium precursors (KNO3, K2CO3, KOH, and C8H5KO4). The synthesis was also carried out using powdered niobium oxide as a precursor, aiming to evaluate the differences between the niobates obtained. The results achieved in this study show that all the niobates produced using ammonium niobate (V) oxalate hydrate were composed solely of the orthorhombic structure of KNbO3, while the materials synthesized using niobium oxide exhibited the rhombohedral structure of KNbO3 along with niobium-rich potassium niobates (K3Nb8O21, K2Nb4O21, and KNb3O8) and residual niobium oxide. This behavior was attributed to the enhanced chemical homogeneity derived from the synthesis using ammonium niobate (V) oxalate hydrate, which facilitated the reaction between the components during the thermal treatment step. Furthermore, the optical and morphological properties of the niobates were considerably influenced by the application of different potassium salts. Owing largely to its morphological and electrical properties, the material synthesized using potassium hydrogen phthalate displayed the highest photocatalytic activity in terms of methylene blue discoloration among the niobates produced using C4H4NNbO9·xH2O. Finally, the proposed piezophotocatalytic ozonation process was found to be a highly efficient strategy for the discoloration of methylene blue, as it successfully harnessed the synergy between the multiple mechanisms involving active radical generation toward the development of a highly promising hybrid advanced oxidation process.

MODIFICATION OF BITUMENS WITH OIL INDUSTRY WASTE

A literature review on the topic of the study has shown that there is not much work with the use of oily waste in the modification of bitumen. Many methods of bitumen modification include the oxidation of a heavy oil residue to obtain the target product and its further compounding with the finished bitumen. Old oil sludge from oil sludge storage tanks has been used as the oil residue. Oil sludge is prepared by dehydration, the water content should not exceed no more than 5 wt. % and separation of mechanical impurities up to a content of not more than 16.4 wt. %. Purpose of the work. The main objective of the study is to develop a technology for modifying oil bitumen with industrial waste for the disposal of oil sludge, and to show the possibility of improving the physical-chemical, rheological characteristics of modified bitumen. Results. In the process of bitumen modification, the physical-chemical characteristics of the modified bitumen have been studied. It has been established that the composition of oil sludge from the Uzen and Zhetybai oilfield of the Mangistau region contains a significant amount of heavy oil residues and a small amount of mechanical impurities. From the conducted laboratory esearch, it has been found that oil sludge can be used as a filler in the modification of bitumen. Conclusion. Used oil sludge can be used as a bituminous base modifier without removing the mechanical impurities. Polymer-bitumen compositions have been prepared and the optimal parameters for the process of preparing polymer-bitumen binders have been determined.

Removal of the red tide dinoflagellate Cochlodinium polykrikoides using chemical disinfectants

For decades, red tide control has been recognized as necessary for mitigating financial damage to fish farms. Chemical disinfectants, frequently used for water disinfection, can reduce the risk of red tides on inland fish farms. This study systematically evaluated four different chemical disinfectants (ozone (O3), permanganate (MnO4−), sodium hypochlorite (NaOCl), and hydrogen peroxide (H2O2)) for their potential use in inland fish farms to control red tides by investigating their (i) inactivation efficacy regarding C. polykrikoides, (ii) total residual oxidant and byproduct formation, and (iii) toxicity to fish. The inactivation efficacy of C. polykrikoides cells by chemical disinfectants from highest to lowest followed the order of O3 > MnO4− > NaOCl > H2O2 for different cell density conditions and disinfectant doses. The O3 and NaOCl treatments generated bromate as an oxidation byproduct by reacting with bromide ions in seawater. The acute toxicity tests of the disinfectants for juvenile red sea bream (Pagrus major) showed that 72-h LC50 values were 1.35 (estimated), 0.39, 1.32, and 102.61 mg/L for O3, MnO4−, NaOCl, and H2O2, respectively. Considering the inactivation efficacy, exposure time of residual oxidants, byproduct formation, and toxicity toward fish, H2O2 is suggested as the most practical disinfectant for controlling red tides in inland fish farms.

Experimental Study on the Preparation of Ultra-Fine Brass Tube Electrodes by Ultrasonic Vibration.

In order to automatically process ultra-fine copper tube electrodes, this study proposes a new method of ultrasonic vibration processing of ultra-fine copper tube, analyzes its processing principle, designs a new set of experimental processing equipment and completes the processing of 1.206 mm inner diameter, 1.276 mm outer diameter with core brass tube. Not only can the copper tube be completed with core decoring, the surface of the processed brass tube electrode also has good integrity. The effect of each machining parameter on the surface roughness of the electrode after machining was investigated by a single-factor experiment and the optimal machining effect was achieved under the conditions of machining gap 0.1 mm, ultrasonic amplitude 0.186 mm, table feed speed 6 mm/min, tube rotation speed 1000 r/min and reciprocating machining two times. The surface roughness was reduced from 1.21 μm before machining to 0.11 μm, and the residual pits, scratches and oxide layer on the surface were completely removed, which greatly improved the surface quality of the brass tube electrode and prolonged its service life.